Anamorphic photography for digital imagers

ABSTRACT

A digital camera comprising a digital image sensor and at least one corrective lens element configured to reduce a blurring of an image in a horizontal or vertical dimension on the digital image sensor. Preferably the digital image sensor is a large digital imager such as a Digital 65 imager.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No. 62/275,733, filed Jan. 6, 2016, the entire contents of which are incorporated herein by reference.

BACKGROUND

Anamorphic camera systems have been utilized to capture a widescreen aspect ratio on film that has a smaller aspect ratio, such as standard 35 mm film. For example, in the standard Panavision anamorphic system, a widescreen image having an aspect ratio of 2.4:1 is compressed in a horizontal dimension by a factor of 2, to be captured on 35 mm film at an aspect ratio of 1.2:1. The horizontal compression allows a higher resolution image to be stored on 35 mm film than would otherwise be allowed if a 2.4:1 aspect ratio were stored on 35 mm film. Anamorphic lens elements are used to compress the original image to be stored on film, and are then used to expand the image again for projection in a cinema or the like.

With the expanded use of digital camera systems, further developments to anamorphic systems are required to address the needs of such digital camera systems. In addition, modifications to the anamorphic compression ratio are needed to address the aspect ratios utilized by digital imaging sensors.

SUMMARY

The systems, apparatuses, and methods disclosed herein are intended to provide for improved anamorphic systems for use with digital camera systems. In addition, modifications to the anamorphic compression ratio disclosed herein address the aspect ratios provided by digital imaging sensors.

In one embodiment, the application discloses a digital camera comprising a digital image sensor and a lens group positioned along an optical axis. The lens group includes at least one anamorphic lens element configured to compress an image in a horizontal or vertical dimension; at least one powered lens element positioned between the at least one anamorphic lens element and the digital image sensor; and at least one corrective lens element positioned between the at least one powered lens element and the digital image sensor, and configured to reduce a blurring of the image in the horizontal or vertical dimension on the digital image sensor or decomposition the image in the horizontal or vertical dimension to substantially equalize the image quality in the horizontal and vertical dimension.

In one embodiment, the application discloses a digital camera system comprising a digital image sensor including an optical low pass filter. The system includes at least one anamorphic lens element configured to compress an image in a horizontal or vertical dimension. The system includes at least one corrective lens element configured to be positioned along an optical axis between the at least one anamorphic lens element and the optical low pass filter, and configured to reduce a blurring of the image in the horizontal or vertical dimension on the digital image sensor caused by the optical low-pass filter.

In one embodiment, the application discloses a digital camera system comprising at least one anamorphic lens element configured to compress an image in a horizontal or vertical dimension by a squeeze ratio of approximately 1.29. The system includes a digital image sensor configured to receive the image compressed by the at least one anamorphic lens element.

BRIEF DESCRIPTION OF THE DRAWINGS

Features and advantages of the systems, apparatuses, and methods as disclosed herein will become appreciated as the same become better understood with reference to the specification, claims, and appended drawings wherein:

FIG. 1 illustrates a schematic view of a camera capturing an image of an object on film.

FIG. 2 illustrates a diagram of blurring using a spherical lens element.

FIG. 3 illustrates a diagram of blurring using an anamorphic lens element.

FIG. 4 illustrates a diagram of a representation of a modulation transfer function (MTF).

FIG. 5 illustrates a schematic view of a camera capturing an image of an object on film, according to an embodiment of the present disclosure.

FIG. 6 illustrates a schematic view of at least one corrective lens element, according to embodiments of the present disclosure.

FIG. 7 illustrates a diagram of optics of a digital camera, according to an embodiment of the present disclosure.

FIG. 8 illustrates a diagram of use of a 1.29 squeeze ratio, according to an embodiment of the present disclosure.

DETAILED DESCRIPTION

FIG. 1 illustrates a schematic view of a camera 10 utilizing an anamorphic process to capture an image of an object 12 on film 14. Anamorphic processes have been used in film applications, namely in motion picture and television filming, to provide a widescreen image capture, yet also enhance the use of the imaging area of a film. An anamorphic process includes compressing the image in a horizontal dimension, or a vertical dimension, to reduce the aspect ratio of the image as it is stored on film. During the projection of the imaged film at a later time, a reverse process is used to expand the image in the horizontal or vertical dimension, to reproduce the original uncompressed image.

An anamorphic process has been used to capture images on 65 millimeter (mm) film in a system referred to as Ultra Panavision. The Ultra Panavision system includes a camera 10 having an anamorphic lens group 16, a powered lens group 18, and 65 mm film 14 for storing the images. The anamorphic lens group 16 includes a plurality of anamorphic lens elements 22. The anamorphic lens elements 22 are configured to compress the image in a dimension, which may be a horizontal or vertical dimension, by a squeeze ratio of between 1.19 to 1.30, which may include a ratio of 1.25, or 1.255. The squeeze ratio is the ratio of the uncompressed image aspect ratio to the compressed image aspect ratio. The anamorphic lens elements 22 may comprise a weak negative afocal system. The anamorphic lens elements 22 may comprise cylindrical lens elements, and/or prism lens elements to produce the compression in the horizontal or vertical dimension. The anamorphic lens elements 22 may include an astigmatizer, which may be similar to the variable astigmatizer disclosed in Wallin, Anamorphosing System, U.S. Pat. No. 2,890,622, issued Jun. 16, 1959, the entire contents of which are incorporated herein by reference. The variable astigmatizer may utilize weak counter-rotating cylinders (e.g., one positive and one negative, or both positive, or both negative) that balance out the axial focus position of the powered and non-powered axes when effectuating focus.

The powered lens group 18 may include spherical lens elements 24 that converge and/or diverge the afocal image produced by the anamorphic lens group 16. The powered lens group 18 may be utilized to effectuate focus of the image. The powered lens group 18 may operate in a similar manner and include similar elements as the focusing lens disclosed in Wallin, U.S. Pat. No. 2,890,622. The powered lens group 18 may be positioned along an optical axis 26 between the anamorphic lens group 16 and the film 14.

The 65 mm film 14 includes an imaging area having a width in a horizontal or vertical dimension of approximately 48.62 mm, and a height in a respective corresponding vertical or horizontal dimension of approximately 22.10 mm. The aspect ratio of the film 14 is approximately 2.20:1. The squeeze ratio of 1.25, or 1.255, allows the system to capture an image with an aspect ratio of approximately 2.76:1 on film having an aspect ratio of 2.20:1. The original widescreen aspect ratio of 2.76:1 is reproduced during projection of the imaged film at a later time. The image quality of the 65 mm film, in combination with the 2.76:1 widescreen aspect ratio, provides an enhanced viewing experience relative to standard widescreen images seen at most cinemas.

An anamorphic process used with digital cameras, and particularly large format digital cameras, has been found to produce problems not typically found with normal film emulsion capture. The use of a digital image sensor in digital cameras produces undesired blurring of the image, particularly in the dimension of anamorphic compression. Digital image sensors may include an optical low-pass filter having supporting filters that the chief ray and associated bundle must pass through, causing an overcorrection/under correction of the normal image correction provided by the camera optics. The filter pack within the camera may overcorrect axial aberrations and undercorrect transverse aberrations. The blurring in the horizontal dimension may include spherical aberration, coma, and astigmatism.

FIG. 2 illustrates a diagram of the blurring occurring in a digital camera using a spherical lens element 28. The spherical lens element 28 compresses the original image, however, any blurring is uniform throughout the image as it is imaged on the digital image sensor.

FIG. 3 illustrates a diagram of the blurring occurring in a digital camera using an anamorphic lens element 30, namely a cylindrical lens element, configured to compress the image in a horizontal or vertical dimension 32. The elements of the digital image sensor produce enhanced blurring of the image in the horizontal or vertical dimension of anamorphic compression.

The digital image sensor may include an optical low-pass filter that may include and that is not limited to a birefringent material. The optical low pass filter is unique to digital cameras, because unlike film cameras the image gets divided up into pixels on the image sensor. The optical low pass filter specifically prevents any spatial frequencies not resolvable by the pixels on the sensor, which is essential to prevent common digital image artifacts. The birefringent material, in combination with the disproportionate magnification in the dimension of anamorphic compression of the image, may result in a modulation transfer function (MTF) of the dimension of anamorphic compression compared to the orthogonal vertical or horizontal dimension that is reduced by a factor of the squeeze ratio. FIG. 4 illustrates an exemplary MTF in a dimension without anamorphic compression, which would be lesser in the dimension of anamorphic compression. Accordingly, the image is blurred in the dimension of anamorphic compression on the digital image sensor to a greater amount than the blurring in the corresponding orthogonal vertical or horizontal dimension. In an embodiment in which the anamorphic compression is in the horizontal dimension, the resulting image is not as sharp horizontally as it is vertically.

FIG. 5 illustrates an embodiment of a digital camera designed to address the blurring in the dimension of anamorphic compression produced by the digital image sensor 38. The digital camera 36 may include the digital image sensor 38, an anamorphic lens group 16, a powered lens group 18, and a corrective lens group 40.

The digital image sensor 38 may include an active imaging area 42 and an optical low-pass filter 44. In one embodiment, the digital image sensor 38 may be configured as a digital sensor with greater than about 2K resolution, and in an example embodiment is a 4K resolution digital sensor, although in other embodiments lesser (2k) or greater resolution (e.g., greater than 4K) may be utilized as desired. In one embodiment, the digital image sensor 38 may have a Digital 65 format. The digital camera 36 may allow for the optics of a film camera to be applied to a digital image sensor 38. The optics of the digital camera 36 may capture an image having a size of approximately 48.62 mm by 22.1 mm, as with 65 mm film, yet at a 4k digital resolution.

In one embodiment, the digital image sensor 38 may be configured to have an active imaging area 42 that is approximately equal to the 48.62 mm by 22.1 mm format of 65 mm film, or greater in area than the format of 65 mm film. In one embodiment, the digital image sensor 38 may be configured to have an active imaging area with a width along the horizontal or vertical dimension that is greater than 35 mm. In one embodiment, the digital image sensor 38 may be configured to have an active imaging area with a width along the horizontal or vertical dimension that is greater than 50 mm. In one embodiment, the digital image sensor 38 may be configured to have an active imaging area with a width along the horizontal or vertical dimension that is between approximately 50 mm and 70 mm.

In one embodiment, the digital image sensor 38 may be configured to have an active imaging area with a height along the vertical or horizontal dimension that is greater than about 20 mm. In one embodiment, the digital image sensor 38 may be configured to have an active imaging area with a height along the vertical or horizontal dimension that is greater than about 30 mm. In one embodiment, the digital image sensor 38 may be configured to have an active imaging area with a height along the vertical or horizontal dimension that is between approximately 25 mm and 35 mm. In one embodiment, the digital image sensor 38 may be configured to have an aspect ratio of approximately 2.2:1. In one embodiment, the heights and widths of the digital image sensor 38 may be combined or varied to different aspect ratios as desired. Preferably, large format digital image sensors 38 are utilized, however, in other embodiments, other formats of digital image sensors 38 may be used as desired. The optical low-pass filter 44 may comprise a single layer or type of material, or multiple layers or types of material.

The anamorphic lens group 16 may be configured similarly as the anamorphic lens group 16 discussed in regard to FIG. 1 . The anamorphic lens group 16 may include a plurality of anamorphic lens elements, or may include at least one anamorphic lens element 22. The at least one anamorphic lens element 22 may be configured to compress an image in the horizontal or vertical dimension. The anamorphic lens group 16 may be configured be integral with the remainder of the lens group, or may be configured to be detachable. In an embodiment in which the lens group 16 is detachable, the digital camera 36 may be configured to alter between anamorphic capture modes and non-anamorphic capture modes.

The powered lens group 18 may be configured similarly as the powered lens group 18 discussed in regard to FIG. 1 . The powered lens group 18 may include a plurality of powered lens elements 24, or may include at least one powered lens element 24. The powered lens elements 24 may include spherical lens elements. The spherical lens elements may be configured to vary the magnification of the image from the anamorphic lens group 16 in all dimensions. The powered lens group 18 may be positioned between the at least one anamorphic lens element 22 and the digital image sensor 38. The powered lens group 18 may be configured be integral with the remainder of the lens group, or may be configured to be detachable.

The corrective lens group 40 may be positioned between the powered lens group 18 and the digital image sensor 38. The corrective lens group 40 may include at least one corrective lens element 48 that is configured to reduce a blurring of the image in the dimension of anamorphic compression on the digital image sensor 38, or configured to decomposition the image in the corresponding orthogonal horizontal or vertical dimension to bring the performance in the dimension of anamorphic compression and the corresponding orthogonal horizontal or vertical dimension to unity, or to substantially equalize the image quality in the two orthogonal dimensions. The reduction of blurring may account for the preferred large format of the digital image sensor 38. The corrective lens group 40 may be positioned as an image side lens group relative to the anamorphic lens group 16, and may serve as a rear optic group comprising the last set of optics prior to the digital image sensor 38. The corrective lens group 40 may be configured to be integral with the remainder of the lens group, or may be configured to be detachable. In an embodiment in which the lens group 16 and corrective lens group 40 are detachable, the digital camera 36 may be configured to alter between anamorphic capture modes and non-anamorphic capture modes.

The at least one corrective lens element 48 may comprise a weak compensator that serves to equalize the asymmetrical blurring caused by the digital image sensor 38, which may include the blurring caused by the optical low-pass filter 44. In one embodiment, the at least one corrective lens element 48 may comprise a cylindrical lens element, which may be a toroidal lens element. The at least one corrective lens element 48 may be self-contained and self-cancelling, yet provide a cylindrical power. The cylindrical lens element may be configured to offset the disproportionate convolution of the image MTF between the dimension of anamorphic compression and the corresponding orthogonal horizontal or vertical dimension when imaged through a birefringent optical low-pass filter 44. In one embodiment, the power of the cylindrical lens element may be dependent on the power provided by the at least one anamorphic lens element 22. Front and rear cylindrical groups may be dependent on each other for optical corrections at the desired large format. As such, the at least one corrective lens element 48 may operate in combination with, and may be dependent on, the at least one anamorphic lens element 22. The rear cylindrical lens element may be configured to correct the spherical aberration, coma, field curvature, and astigmatism caused by the optical low-pass filter 44.

In one embodiment, the at least one corrective lens element 48 may comprise a birefringent material. The birefringent material may have an orientation within the corrective lens group 40 that serves to reduce the asymmetrical blurring caused by the digital image sensor 38, which may include the blurring caused by the optical low-pass filter 44. The birefringent material may be configured to balance out the asymmetrical blurring by providing a calculated amount of image decomposition, which may be a function of the squeeze ratio. A single layer or type of birefringent material, or multiple layers or types of birefringent material may be utilized as desired. The birefringent material may be configured to correct the spherical aberration, coma, field curvature, and astigmatism caused by the optical low-pass filter 44.

In one embodiment, the at least one corrective lens element 48 may include a combination of a cylindrical lens element, such as a toroidal lens element, and a birefringent material. In one embodiment, the corrective lens group 40 may be configured as a group of adaptive optics positioned on the image side of the anamorphic lens group 16. In one embodiment, the anamorphic lens group 16 may be configured as a cylindrical lens group that operates in combination with the adaptive optics of the corrective lens group 40.

FIG. 6 illustrates an embodiment of the at least one corrective lens element 48 comprising a birefringent material 48 a. The birefringent material in one embodiment may comprise quartz, although in other embodiments, a different material may be utilized as desired. The birefringent material may be oriented orthogonal to the powered dimension. FIG. 6 illustrates an embodiment of the at least one corrective lens element 48 comprising a cylindrical lens element, which may be a toroidal lens element 48 b. The toroidal lens element may comprise a weak toroidal surface facing the object side of the corrective lens group 40.

FIG. 7 illustrates a top view of the optics of the digital camera 36 before and after correction by the at least one corrective lens element 48. Blurring in the dimension of anamorphic compression is reduced.

The anamorphic lens group 16, the powered lens group 18, and the corrective lens group 40 may in combination comprise a lens group that is positioned along an optical axis 26. The anamorphic lens group 16, and the corrective lens group 40 may operate on front and rear sides of the powered lens group 18.

In one embodiment, the squeeze ratio of the anamorphic lens group 16 may be 2, for example in an embodiment in which the standard 2.4:1 Panavision widescreen aspect ratio is desired (for a captured 1.2:1 aspect ratio). In one embodiment, the squeeze ratio of the anamorphic lens group 16 may be set to approximately 1.34, for example in an embodiment in which a captured 1.78 aspect ratio is desired, in a manner described in Miyagishima et al., Anamorphic Three-Perforation Imaging System, U.S. Pat. No. 7,148,947, issued Dec. 12, 2006, the entire contents of which are incorporated herein by reference. In one embodiment, the squeeze ratio of the anamorphic lens group 16 may be varied as desired.

Referring to FIG. 8 , in one embodiment, the squeeze ratio of the anamorphic lens group 16 a may be varied by about 3% of 1.25, or 1.255, to provide an anamorphic lens group 16 b having a squeeze ratio of approximately 1.29. In one embodiment, the 3% adjustment may be achieved by introducing or enhancing the size of an air gap between the front element of the anamorphic lens group 16 b and the astigmatizers.

The 1.29 squeeze ratio may be utilized with both a Digital 65 digital image sensor, as well as a Super 35 digital image sensor. In an embodiment in which a Digital 65 digital image sensor is used, the change in compression ratio may be essentially negligible as it is within the compression ratio tolerances that already exist in the anamorphic lens group 16 b, for example within the astigmatizers. Accordingly, a 2.76:1 aspect ratio may still result upon expansion.

In an embodiment in which a Super 35 digital image sensor is used, the 1.29 squeeze ratio allows a 2.4:1 image to be captured at a 1.78:1 aspect ratio, with only an approximately 4% loss of use of the active image area. The entire width of the sensor may be used, which allows for a true 4k resolution hybrid 2.4:1 aspect ratio anamorphic scan. This may be an improvement over traditional anamorphic capture at a squeeze ratio of 2, which is currently limited to a 2k resolution.

The captured 1.78 aspect ratio (Super 35), or the captured 2.20 aspect ratio (Digital 65) may be converted to alternative desired aspect ratios in the manner described in Miyagishima et al., U.S. Pat. No. 7,148,947.

The processes disclosed herein of capturing an image at a squeeze ratio may be practiced as a method within the scope of this application. In addition, use of the at least one corrective lens element 48 disclosed herein may be practiced as a method within the scope of this application. Other methods disclosed herein may be practiced within the scope of this application. In addition, the at least one corrective lens element 48, separate or in combination with other of the optics disclosed herein may comprise a standalone feature within the scope of this application.

In closing, it is to be understood that although aspects of the present specification are highlighted by referring to specific embodiments, one skilled in the art will readily appreciate that these disclosed embodiments are only illustrative of the principles of the subject matter disclosed herein. Therefore, it should be understood that the disclosed subject matter is in no way limited to a particular methodology, protocol, and/or reagent, etc., described herein. As such, various modifications or changes to or alternative configurations of the disclosed subject matter can be made in accordance with the teachings herein without departing from the spirit of the present specification. Lastly, the terminology used herein is for the purpose of describing particular embodiments only, and is not intended to limit the scope of systems, apparatuses, and methods as disclosed herein, which is defined solely by the claims. Accordingly, the systems, apparatuses, and methods are not limited to that precisely as shown and described.

Certain embodiments of systems, apparatuses, and methods are described herein, including the best mode known to the inventors for carrying out the same. Of course, variations on these described embodiments will become apparent to those of ordinary skill in the art upon reading the foregoing description. The inventor expects skilled artisans to employ such variations as appropriate, and the inventors intend for the systems, apparatuses, and methods to be practiced otherwise than specifically described herein. Accordingly, the systems, apparatuses, and methods include all modifications and equivalents of the subject matter recited in the claims appended hereto as permitted by applicable law. Moreover, any combination of the above-described embodiments in all possible variations thereof is encompassed by the systems, apparatuses, and methods unless otherwise indicated herein or otherwise clearly contradicted by context.

Groupings of alternative embodiments, elements, or steps of the systems, apparatuses, and methods are not to be construed as limitations. Each group member may be referred to and claimed individually or in any combination with other group members disclosed herein. It is anticipated that one or more members of a group may be included in, or deleted from, a group for reasons of convenience and/or patentability. When any such inclusion or deletion occurs, the specification is deemed to contain the group as modified thus fulfilling the written description of all Markush groups used in the appended claims.

Unless otherwise indicated, all numbers expressing a characteristic, item, quantity, parameter, property, term, and so forth used in the present specification and claims are to be understood as being modified in all instances by the term “about.” As used herein, the term “about” means that the characteristic, item, quantity, parameter, property, or term so qualified encompasses an approximation that may vary. The terms “approximate[ly]” and “substantial[ly]” represent an amount that may vary from the stated amount, yet is capable of performing the desired operation or process discussed herein.

The terms “a,” “an,” “the” and similar referents used in the context of describing the systems, apparatuses, and methods (especially in the context of the following claims) are to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g., “such as”) provided herein is intended merely to better illuminate the systems, apparatuses, and methods and does not pose a limitation on the scope of the systems, apparatuses, and methods otherwise claimed. No language in the present specification should be construed as indicating any non-claimed element essential to the practice of the systems, apparatuses, and methods.

All patents, patent publications, and other publications referenced and identified in the present specification are individually and expressly incorporated herein by reference in their entirety for the purpose of describing and disclosing, for example, the compositions and methodologies described in such publications that might be used in connection with the systems, apparatuses, and methods. These publications are provided solely for their disclosure prior to the filing date of the present application. Nothing in this regard should be construed as an admission that the inventors are not entitled to antedate such disclosure by virtue of prior invention or for any other reason. All statements as to the date or representation as to the contents of these documents is based on the information available to the applicants and does not constitute any admission as to the correctness of the dates or contents of these documents. 

What is claimed is:
 1. A lens system for use with a camera, comprising: a front anamorphic lens group comprising a plurality of anamorphic lens elements, wherein the front anamorphic lens group is positioned at an object side of the lens system and is configured to produce an image that is compressed in a horizontal or vertical dimension that has a reduced aspect ratio; a corrective lens group that is separate from the front anamorphic lens group and that is positioned adjacent the front anamorphic lens group, wherein the corrective lens group is aligned along and shares the same optical axis of the front anamorphic lens group to receive the compressed image produced by the front anamorphic lens group; and a digital image sensor separate from and positioned to share the same optical axis of the anamorphic lens group and the corrective lens group, wherein the corrective lens group is interposed between the front anamorphic lens group and the digital image sensor, and wherein the corrective lens group is configured to improve an optical quality of the image at the digital image sensor by reducing a blurring of the image as produced by the digital image sensor.
 2. The lens system as recited in claim 1, wherein the corrective lens group comprises one or more of a toroidal lens element or a birefringent material.
 3. The lens system as recited in claim 1, comprising a powered lens group that is separate from and that is interposed between the front anamorphic lens group and the corrective lens group, wherein the corrective lens group comprises a number of powered lens elements, and wherein the powered lens group is aligned to share the same optical axis of the anamorphic lens group and the corrective lens group.
 4. The lens system as recited in claim 1, wherein the digital image sensor is aligned to share the same optical axis of the anamorphic lens group and the corrective lens group and receives the image produced by the corrective lens group.
 5. The lens system as recited in claim 1, wherein the digital image sensor has an active imaging area with a width along the horizontal or vertical dimension that is greater than about 35 millimeters.
 6. The lens system as recited in claim 1, wherein the digital image sensor comprises an optical low-pass filter, and wherein the blurring of the image is caused by the optical low-pass filter.
 7. The lens system as recited in claim 6, comprising a powered lens group that is separate from and interposed between the front anamorphic lens group and the digital image sensor, wherein the powered lens group comprises more than one powered lens elements, and wherein the powered lens group is aligned to share the same optical axis of the anamorphic lens group and the corrective lens group.
 8. The lens system as recited in claim 1, wherein the front anamorphic lens group is configured to compress the image in a dimension of anamorphic compression by a squeeze ratio of at least 1.19.
 9. A lens system for use with a digital camera, comprising: front anamorphic lens group comprising a plurality of anamorphic lens elements and positioned at an object side of the lens system and configured to receive an image and compress the image in a horizontal or vertical direction by a squeeze ratio of at least 1.19; and a corrective lens group that is separate from the front anamorphic lens group and that is configured to reduce a blurring of the image produced by the front anamorphic lens group in the direction of compression as produced by a digital image sensor positioned to receive an image from the corrective lens group; wherein the front anamorphic lens group and the corrective lens group are aligned along a common optical axis passing through each of the front anamorphic lens group and the corrective lens group.
 10. The lens system as recited in claim 9, wherein the corrective lens group is interposed between the digital image sensor and the front anamorphic lens group, and wherein the digital image sensor shares the same optical axis as the front anamorphic lens group.
 11. The lens system as recited in claim 9, wherein the corrective lens group comprises a birefringent material.
 12. The lens system as recited in claim 9, wherein the corrective lens group comprises a toroidal lens element.
 13. The lens system as recited in claim 9, comprising a powered lens group that is separate from and that is interposed between the front anamorphic lens group and the corrective lens group, and wherein the powered lens group shares the same optical axis as the front anamorphic lens group.
 14. The lens system as recited in claim 9, wherein the digital image sensor comprises an optical low-pass filter.
 15. The lens system as recited in claim 14, wherein the blurring of the image is caused by the optical low-pass filter.
 16. A method for improving an optical quality of an image produced by a lens system used with a camera comprising a digital image sensor, the method comprising: producing an optical image by a front anamorphic lens group positioned at an object side of the lens system and having an optical axis, the front anamorphic lens group comprising more than one anamorphic lens elements and being configured to compress the image in a horizontal or vertical dimension and produce an image having a reduced aspect ratio; and treating the compressed image by passing the compressed image through a corrective lens group that is separate from the front anamorphic lens group and that shares the same optical axis as the front anamorphic lens group, wherein the corrective lens group is configured to improve an optical quality of the compressed image by reducing blurring of the image that is produced by the digital image sensor, wherein the digital image sensor is positioned to receive the treated image from the corrective lens group.
 17. The method as recited in claim 16, wherein during the step of treating the compressed image, the corrective lens group is configured to reduce blurring of the image that is produced by an optical low-pass filter used with the digital image sensor, and comprising after the step of treating, passing the image from the corrective lens group to the optical low-pass filter.
 18. The method as recited in claim 16, wherein the corrective lens group comprises at least one of a birefringent material or a toroidal lens element.
 19. The method as recited in claim 16, wherein before the step of treating, passing the compressed image from the front anamorphic lens group to a powered lens group that is separate from the front anamorphic lens group and the corrective lens group, wherein the powered lens group comprises more than one powered lens elements, and wherein the powered lens group shares the same optical axis as the front anamorphic lens group. 